conference: use TrackID as identifier for tracks

Theoretically we don't need to use a combination of TrackID and StreamID
to uniquely identify tracks inside as long as the GUIDs are used for the
tracks.

Closes #56.

pkg/conference/data_channel_message_processor.go

@@ -19,7 +19,7 @@ func (c *Conference) processSelectDCMessage(participant *Participant, msg event.
 	if len(tracks) != len(msg.Start) {
 		for _, expected := range msg.Start {
 			found := slices.IndexFunc(tracks, func(track *webrtc.TrackLocalStaticRTP) bool {
-				return track.StreamID() == expected.StreamID && track.ID() == expected.TrackID
+				return track.ID() == expected.TrackID
 			})
 
 			if found == -1 {

pkg/conference/matrix_message_processor.go

@@ -65,7 +65,7 @@ func (c *Conference) onNewParticipant(participantID ParticipantID, inviteEvent *
 			logger:          logger,
 			remoteSessionID: inviteEvent.SenderSessionID,
 			streamMetadata:  inviteEvent.SDPStreamMetadata,
-			publishedTracks: make(map[event.SFUTrackDescription]PublishedTrack),
+			publishedTracks: make(map[string]PublishedTrack),
 		}
 
 		c.participants[participantID] = participant

pkg/conference/participant.go

@@ -34,7 +34,7 @@ type Participant struct {
 	peer            *peer.Peer[ParticipantID]
 	remoteSessionID id.SessionID
 	streamMetadata  event.CallSDPStreamMetadata
-	publishedTracks map[event.SFUTrackDescription]PublishedTrack
+	publishedTracks map[string]PublishedTrack
 }
 
 func (p *Participant) asMatrixRecipient() signaling.MatrixRecipient {

pkg/conference/peer_message_processor.go

@@ -21,26 +21,19 @@ func (c *Conference) processLeftTheCallMessage(participant *Participant, msg pee
 
 func (c *Conference) processNewTrackPublishedMessage(participant *Participant, msg peer.NewTrackPublished) {
 	participant.logger.Infof("Published new track: %s", msg.Track.ID())
-	key := event.SFUTrackDescription{
-		StreamID: msg.Track.StreamID(),
-		TrackID:  msg.Track.ID(),
-	}
 
-	if _, ok := participant.publishedTracks[key]; ok {
-		c.logger.Errorf("Track already published: %v", key)
+	if _, ok := participant.publishedTracks[msg.Track.ID()]; ok {
+		c.logger.Errorf("Track already published: %v", msg.Track.ID())
 		return
 	}
 
-	participant.publishedTracks[key] = PublishedTrack{track: msg.Track}
+	participant.publishedTracks[msg.Track.ID()] = PublishedTrack{track: msg.Track}
 	c.resendMetadataToAllExcept(participant.id)
 }
 
 func (c *Conference) processPublishedTrackFailedMessage(participant *Participant, msg peer.PublishedTrackFailed) {
 	participant.logger.Infof("Failed published track: %s", msg.Track.ID())
-	delete(participant.publishedTracks, event.SFUTrackDescription{
-		StreamID: msg.Track.StreamID(),
-		TrackID:  msg.Track.ID(),
-	})
+	delete(participant.publishedTracks, msg.Track.ID())
 
 	for _, otherParticipant := range c.participants {
 		if otherParticipant.id == participant.id {
@@ -116,9 +109,9 @@ func (c *Conference) processDataChannelAvailableMessage(participant *Participant
 
 func (c *Conference) processForwardRTCPMessage(msg peer.RTCPReceived) {
 	for _, participant := range c.participants {
-		for _, publishedTrack := range participant.publishedTracks {
-			if publishedTrack.track.StreamID() == msg.StreamID && publishedTrack.track.ID() == msg.TrackID {
-				err := participant.peer.WriteRTCP(msg.Packets, msg.StreamID, msg.TrackID, publishedTrack.lastPLITimestamp)
+		for id, publishedTrack := range participant.publishedTracks {
+			if id == msg.TrackID {
+				err := participant.peer.WriteRTCP(msg.Packets, msg.TrackID, publishedTrack.lastPLITimestamp)
 				if err == nil {
 					publishedTrack.lastPLITimestamp = time.Now()
 				}

pkg/conference/state.go

@@ -59,6 +59,7 @@ func (c *Conference) removeParticipant(participantID ParticipantID) {
 	for _, publishedTrack := range participant.publishedTracks {
 		obsoleteTracks = append(obsoleteTracks, publishedTrack.track)
 	}
+
 	for _, otherParticipant := range c.participants {
 		otherParticipant.peer.UnsubscribeFrom(obsoleteTracks)
 	}
@@ -98,7 +99,7 @@ func (c *Conference) getTracks(identifiers []event.SFUTrackDescription) []*webrt
 	for _, participant := range c.participants {
 		// Check if this participant has any of the tracks that we're looking for.
 		for _, identifier := range identifiers {
-			if track, ok := participant.publishedTracks[identifier]; ok {
+			if track, ok := participant.publishedTracks[identifier.TrackID]; ok {
 				tracks = append(tracks, track.track)
 			}
 		}

pkg/peer/messages.go

@@ -41,7 +41,6 @@ type DataChannelMessage struct {
 type DataChannelAvailable struct{}
 
 type RTCPReceived struct {
-	Packets  []rtcp.Packet
-	StreamID string
-	TrackID  string
+	TrackID string
+	Packets []rtcp.Packet
 }

pkg/peer/peer.go

@@ -112,21 +112,21 @@ func (p *Peer[ID]) SubscribeTo(track *webrtc.TrackLocalStaticRTP) error {
 				p.logger.WithError(err).Warn("failed to read RTCP on track")
 			}
 
-			p.sink.Send(RTCPReceived{Packets: packets, TrackID: track.ID(), StreamID: track.StreamID()})
+			p.sink.Send(RTCPReceived{Packets: packets, TrackID: track.ID()})
 		}
 	}()
 
 	return nil
 }
 
-func (p *Peer[ID]) WriteRTCP(packets []rtcp.Packet, streamID string, trackID string, lastPLITimestamp time.Time) error {
+func (p *Peer[ID]) WriteRTCP(packets []rtcp.Packet, trackID string, lastPLITimestamp time.Time) error {
 	const minimalPLIInterval = time.Millisecond * 500
 
 	packetsToSend := []rtcp.Packet{}
 	var mediaSSRC uint32
 	receivers := p.peerConnection.GetReceivers()
 	receiverIndex := slices.IndexFunc(receivers, func(receiver *webrtc.RTPReceiver) bool {
-		return receiver.Track().ID() == trackID && receiver.Track().StreamID() == streamID
+		return receiver.Track().ID() == trackID
 	})
 
 	if receiverIndex == -1 {